SCAN18373T Datasheet | National Semiconductor

SCAN18373T Transparent Latch with TRI-STATE Outputs September 1998 SCAN18373T Transparent Latch with TRI-STATE ® Outputs General Description The SCAN18373T is a high speed, low-power transparent latch featuring separate data inputs organized into dual 9-bit bytes with byte-oriented latch enable and output enable control signals. This device is pliant with IEEE 1149.1 Standard Test Access Port and Boundary Scan Architecture with the incorporation of the defined boundary-scan test logic and test access port consisting of Test Data Input (TDI), Test Data Out (TDO), Test Mode Select (TMS), and Test Clock (TCK). Features n n n n n n n n n n IEEE 1149.1 (JTAG) pliant Buffered active-low latch enable TRI-STATE outputs for bus-oriented applications 9-bit data busses for parity applications Reduced-swing outputs source 24 m A/sink 48 m A Guaranteed to drive 50Ω transmission line to TTL input levels of 0.8V and 2.0V TTL patible inputs 25 mil pitch Cerpack packaging Includes CLAMP and HIGHZ instructions Standard Microcircuit Drawing (SMD) 5962-9311801 Connection Diagram Pin Names AI(0- 8), BI(0- 8) ALE, BLE AOE1, BOE1 AO(0- 8), BO(0- 8) Description Data Inputs Latch Enable Inputs TRI-STATE Output Enable Inputs TRI-STATE Latch Outputs Truth Tables Inputs ALE X H H L AOE1 H L L L Inputs BLE X H H L BOE1 H L L L BI (0- 8) X L H X Z L H BO0 AI (0- 8) X L H X Z L H AO0 BO (0- 8) AO (0- 8) H = HIGH Voltage Level L = LOW Voltage Level X = Immaterial Z = High Impedance AO0 = Previous AO before H-to-L transition of ALE BO0 = Previous BO before H-to-L transition of BLE Functional Description DS100321-1 The SCAN18373T consists of two sets of nine D-type latches with TRI-STATE standard outputs. When the Latch Enable (ALE or BLE) input is HIGH, data on the inputs (AI(0- 8) or BI(0- 8) ) enters the latches. In this condition the latches are transparent, i.e., a latch output will change state each time its input changes. When Latch Enable is LOW, the latches store the information...